Rotating Silver Egg

The exhibit features interactive games that allow participants to understand the working principle of three-phase induction motors and related knowledge of rotating magnetic fields.

Interaction type: Electromechanical, hands-on. The unit is designed for unsupervised public use: controls are recessed or shielded, moving parts are enclosed, and the interface is operable by a child of about six with no instruction. Where a screen is used, the language can be switched without changing the hardware, and the content can be replaced on site.

The rotating magnetic field is the fundamental condition for the mutual conversion between electrical energy and rotating mechanical energy. Usually, the stator of a three-phase AC motor has symmetrical three-phase windings (see armature winding). When an alternating current is applied to any phase winding, a pulsating magnetic field is generated. But if a balanced three-phase current is passed through a three-phase symmetrical winding, a magnetic field rotating in space will be generated. The axis of symmetry of the magnetic field, φ, rotates with time, and its rotational speed ns is determined by the current frequency f and the number of magnetic pole pairs P.